1. Field of the Invention
The present invention relates to an electronic watt-hour meter that may be applied to a general power grid and an electronic watt-hour measuring method.
2. Description of the Related Art
In general, an inductive watt-hour meter has mainly been used as a watt-hour meter. Recently, demand for a watt-hour meter has greatly increased with increased interest in a smart grid.
A smart grid is an intelligent power grid system having increased efficiency by allowing a supplier to interact with a consumer through a combination of information and communications technologies with a process of power generation, power transportation, and power consumption. The power supplier may check a user's predicted power consumption in real time to determine supply and demand requirements of power and the user may check power consumption and power rate in real time to determine his/her power use pattern.
For the smart grid, there is a need for an electronic watt-hour meter that accurately calculates power consumption and converts the calculated power consumption into digital information, an electronic watt-hour measuring method, and a communications technology device transmitting the converted digital information.
The electronic watt-hour meter according to the related art senses three-phase voltage and three-phase current and converts and processes the three-phase voltage and the three-phase current into digital signals, such that it requires at least six signal converters. Therefore, a method of using a multiplexer has been proposed. The method inputs the sensed three-phase voltage (current), to the multiplexer, and the sensed three-phase voltage (current) is in turn input to the signal converters through time distribution. The sensed voltage (current) converted into the digital signals in the signal converters are input to an calculating unit via a demultiplexer and is used to calculate, for example, effective power use, reactive power use and the like.
However, the electronic watt-hour meter using a multiplexer according to the related art is affected by interference between signals having different phases and random noise, which may degrades the accuracy of watt-hour calculation.